The present invention relates to a method of performing continuous wet heat treatment of a cloth advantageously in the processing thereof, such as in scouring, bleaching, desizing, weight reduction and dyeing. The present inventive method is particularly suitable for dyeing a cloth containing polyester fibers by wet heat treatment.
In dyeing cloths such as woven and knitted goods, for instance, it has been well known that an excellent and high speed dyeing can be done, giving a superior dye fixability, by subjecting a cloth impregnated with a dye solution to a wet heat treatment in a high pressure steamer under high temperature and high pressure water vapor to fix the dye firmly on the cloth, and a discontinuous dyeing method such as a batch process has been adopted therefor conventionally. However, in such a discontinuous method, there are useless features, such as the energy loss in replacing cloth and the loss of dye solution. Particularly, in a commercial mass production, the replacement of cloth in a batch consumes largely labor and cost, and moreover, uniform dyeing cannot be expected.
Under such circumstances, a high pressure steamer for continuous use has been developed by the present applicant, in which a cloth impregnated with a dye solution is transported continuously through the high pressure steamer body by maintaining the interior thereof with a saturated water vapor at about 160.degree. C., and the apparatus is under practical application.
However, since the apparatus is capable of raising the temperature of the interior very high, for instance up to about 160.degree. C. and the wet heat treatment is done at about this temperature, the apparatus becomes a giant one chiefly from the point of the resistance against pressure, and consequently there occur such defects that the construction cost is high, the transportation and establishment of the apparatus are not convenient and a large space is needed for its establishment, thus elevating the fixed costs remarkably.
In the high pressure steamer, further, whereas liquid tanks are provided in the steamer body to take in treating liquids so as to finish the dyeing and preliminary washing of the cloth in the course of transporting the cloth through the steamer body, the size of a liquid tank is unavoidably restricted in a steamer body with a limited space and consequently boiling treatment and particularly preliminary washing can hardly be done sufficiently in situ in the steamer body, so that there occurs such a drawback that it needs a a large amount of water and a prolonged time in washing the cloth after it is taken out from the steamer.